KR100571270B1 - Pouch Type Lithium Secondary Battery - Google Patents

Abstract

The present invention relates to a pouch-type lithium secondary battery having improved stability by simultaneously connecting the electrode lead and the connecting circuit electrically acting as a positive temperature element, the pouch-type lithium secondary battery of the present invention is a first electrode An electrode assembly having a plate, a second electrode plate, and a separator interposed between the first electrode plate and the second electrode plate; A pouch case having a space for accommodating the electrode assembly; A protection circuit module for controlling charging and discharging of the electrode assembly, the protective circuit module including a bonding pad at a portion thereof; And a connection lead electrically connected to the bonding pad and the electrode assembly and blocking the circuit when the temperature rises.

Pouch type lithium secondary battery, positive temperature element, connection lead, junction pad

Description

Pouch type lithium secondary battery {Pouch Type Li Secondary Battery}

Figure 1a is a perspective view showing a state before the pouch packaging material of the pouch-type lithium secondary battery according to an embodiment of the present invention is sealed.

1B is a plan view illustrating a connection between a protective electrode assembly, a circuit module, and a connection lead of a pouch-type lithium secondary battery according to an embodiment of the present invention.

Figure 1c is a perspective view showing a state after the pouch packaging material of the pouch-type lithium secondary battery according to an embodiment of the present invention is sealed.

Figure 2a is a perspective view for explaining the connection lead of the pouch-type lithium secondary battery according to an embodiment of the present invention.

2B is a cross-sectional view illustrating a connection lead of a pouch-type lithium secondary battery according to an embodiment of the present invention.

3A is a perspective view illustrating a connection lead of a pouch-type lithium secondary battery according to another embodiment of the present invention.

3B is a cross-sectional view illustrating a connection lead of a pouch-type lithium secondary battery according to another embodiment of the present invention.

(Explanation of symbols for main parts of drawing)

100; Pouch type lithium secondary battery 110; Electrode assembly

111; A first electrode plate 112; Second electrode plate

113; Separator 114; First electrode tab

115; Second electrode tab 116; Insulation tape

120; Pouch sheath 121; if

121a; Space 122; Top

123; Junction 130; Protection circuit board

135; Bonding pads 140, 145, 245; Connection lead

The present invention relates to a lithium secondary battery, and more particularly, to a pouch-type lithium secondary battery having improved stability by simultaneously performing the role of a positive temperature element connecting electrode electrically connecting the electrode assembly and the protection circuit.

Recently, compact and lightweight electric / electronic devices such as cellular phones, notebook computers, camcorders, etc. have been actively developed and produced. These portable electric / electronic devices have a battery pack that can be operated in a place where no separate power source is provided. The built-in battery pack includes at least one battery therein for outputting a predetermined level of voltage for driving the portable electric / electronic device for a period of time.

In view of economical aspects, the battery pack employs a secondary battery capable of charging and discharging. Representative secondary batteries include lithium secondary batteries such as nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.

In particular, the lithium secondary battery has an operating voltage of 3.6 V, which is three times higher than that of a nickel-cadmium battery or a nickel-hydrogen battery, which is widely used as a power source for portable electronic equipment, and is rapidly expanding in terms of high energy density per unit weight. to be.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. In general, a battery is classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte, and a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery. Moreover, although a lithium secondary battery is manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

Typically, the pouch-type lithium secondary battery of the lithium secondary battery is a pouch packaging material is usually composed of a multilayer layer of a metal foil layer and a synthetic resin layer covering the same, when using this than the cylindrical or square lithium secondary battery using a metal can Since the weight can be remarkably reduced, the weight reduction of the lithium secondary battery has been developed toward the pouch type lithium secondary battery.

Such a pouch-type lithium secondary battery has an electrode assembly in a form in which a plurality of separators interposed between a positive electrode and a negative electrode plate and the positive electrode and the negative electrode plate are accommodated in a pouch packaging material, and the anode is externally disposed on one side of the pouch packaging material. The tab and the negative electrode tab protrude and connect with the protection circuit module.

The protecting circuit module (PCM) generally has a structure including various protection circuits and positive temperature elements on a printed circuit board (PCB).

However, since the positive temperature element is mounted in the protection circuit module, there is a problem that the reaction rate of the positive temperature element is slow.

If the reaction rate of the positive temperature element as described above is slow, there is a risk of explosion of the lithium secondary battery.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art. The present invention provides a pouch-type lithium secondary battery having improved stability by simultaneously performing a role of a positive temperature element in which a connection lead electrically connecting an electrode assembly and a protection circuit. The object is to provide a battery.

Pouch-type lithium secondary battery of the present invention for achieving the above object comprises an electrode assembly having a first electrode plate, a second electrode plate and a separator interposed between the first electrode plate and the second electrode plate; A pouch case having a space for accommodating the electrode assembly; A protection circuit module for controlling charging and discharging of the electrode assembly, the protective circuit module including a bonding pad at a portion thereof; And a connection lead electrically connected to the bonding pad and the electrode assembly and blocking the circuit when the temperature rises.

In addition, the pouch-type lithium secondary battery of the present invention includes an electrode assembly having a first electrode plate, a second electrode plate and a separator interposed between the first electrode plate and the second electrode plate; A pouch case having a space for accommodating the electrode assembly; A protection circuit module for controlling charging and discharging of the electrode assembly, the protective circuit module including a bonding pad at a portion thereof; And a connection lead electrically connected to the junction pad and the electrode assembly and integrated with a positive temperature element.

In an embodiment of the invention, the bond pad is made of nickel.

The connection lead also includes an upper conductive film, a lower conductive film, and a positive temperature element material layer interposed between the upper conductive film and the lower conductive film. In this case, any one of the upper conductive film and the lower conductive film is electrically connected to the electrode assembly, and the other of the upper conductive film and the lower conductive film is electrically connected to the bonding pad.

The connection lead may further include a positive temperature element portion including an upper conductive layer, a lower conductive layer, and a positive temperature element material layer interposed between the upper conductive layer and the lower conductive layer, and a protective circuit electrically connected to the bonding pad. It may have a structure including a module connection. At this time, any one of the upper conductive film and the lower conductive film is electrically connected to the protective circuit module connection part, and the other of the upper conductive film and the lower conductive film is electrically connected to the electrode assembly.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1a is a perspective view showing a state before the pouch packaging material of the pouch-type lithium secondary battery according to an embodiment of the present invention, Figure 1b is a protective electrode of the pouch-type lithium secondary battery according to an embodiment of the present invention 1 is a plan view illustrating a connection between an assembly, a circuit module, and a connection lead, and FIG. 1C is a perspective view illustrating a state after the pouch exterior material of the pouch-type lithium secondary battery according to the exemplary embodiment of the present invention is sealed.

1A to 1C, the pouch-type lithium secondary battery 100 according to the exemplary embodiment of the present invention may include an electrode assembly 110, a pouch packaging material 120 accommodating the electrode assembly 110, and The protection circuit module 130 for controlling the charging and discharging of the electrode assembly 110 and the electrode assembly 110 and the protection circuit module 130 are electrically connected to each other and simultaneously serve as positive temperature elements. It consists of a structure provided with the connection leads 140 and 145.

The electrode assembly 110 may be coated with any one of a positive electrode active material and a negative electrode active material, for example, a first electrode plate 111 coated with a positive electrode active material, another one of a positive electrode active material and a negative electrode active material, for example, a negative electrode active material. The second electrode plate 112, the first electrode plate 111, and the second electrode plate 112 positioned between the first electrode plate 111 and the second electrode plate 112. And a separator 113 for preventing the movement of lithium ions. In addition, the first electrode plate 111 is generally made of aluminum (Al) material, and a first electrode tab 114 is formed to protrude a predetermined length to the upper side and serve as a positive electrode tab. The second electrode plate 112 is generally made of a nickel (Ni) material, but a second electrode tab 115 is formed to protrude a lower length to serve as a negative electrode tab. It is not limited. In addition, an insulating tape 116 may be further provided to prevent a short circuit between the first electrode tab 114 and the second electrode tab 115 and the pouch case 120.

In this case, a chalcogenide compound is used as the cathode active material, and complex metal oxides such as LiCoO 2, LiMn 2 O 4, LiNiO 2, LiNi 1-x Cox O 2 (0 <x <1), and LiMnO 2 are used. As the negative electrode active material, carbon (C) -based materials, Si, Sn, tin oxides, composite tin alloys, transition metal oxides, lithium metal nitrides, or lithium metal oxides are used. Also, in general, the anode electrode plate is made of aluminum (Al), the cathode electrode plate is made of copper (Cu), and the separator is generally made of polyethylene (PE) or polypropylene (PP). It does not limit the above materials.

The pouch packaging material 120 includes a bottom surface 121 formed with a space 121a in which the electrode assembly 110 is accommodated, and an upper surface 122 covering a bottom surface 121 with the space 121a formed therein. The edge of the space 121a of the bottom surface 121 is a junction portion 123 that receives the electrode assembly 110 in the pouch packaging material 120 and then bonds and seals the electrode assembly 110. In addition, the space 121a for accommodating the electrode assembly 110 is formed through a press process or the like. In addition, the pouch sheathing member 120 accommodates the electrode assembly 110 in the space 121a of the lower surface 121, and then covers and seals the upper surface 122.

The first electrode tab 114 and the second electrode tab 115 of the electrode assembly 110 are drawn out through one side of the pouch packaging material 120 junction 123, and the first electrode tab 114 and the second electrode tab 115 are electrically connected to the protection circuit module 130 through the first connection lead 140 and the second connection lead 145.

The protection circuit module 130 controls the charging, discharging, and malfunction of the electrode assembly 110. For example, the protection circuit module 130 blocks the overcurrent when an overcurrent flows from the electrode assembly 110. do. In addition, the protection circuit module 130 is at least one of which is bonded to the first connection lead 140 and the second connection lead 145, for example, the second electrode tab 115 serving as a negative electrode tab. And a bonding pad 135 made of a conductive metal material such as nickel (Ni) at a portion to which the second connection lead 145 to be bonded is joined. The bonding pad 135 is for facilitating the bonding between the second connection lead 145 and the protection circuit module 130. In addition, although not shown in the drawings, the protection circuit module 130 is generally made of a structure having various protection circuits.

The connection leads 140 and 145 may include first connection leads electrically connecting the first electrode tab 114 and the second electrode tab 115 of the electrode assembly 110 to the protection circuit module 130. The second electrode tab (140) and the second connection lead (145), and acting as at least one of the first connection lead (140) and the second connection lead (145), for example, as a negative electrode tab ( A second connection lead 145 electrically connected to 115 simultaneously serves as a positive temperature element.

One end of the first connection lead 140 and the second connection lead 145 is welded to and coupled to the ends of the first electrode tab 114 and the second electrode tab 115, and the first connection lead 140. ) And the other end of the second connection lead 145 are bonded to the protection circuit module 130 to electrically connect the first electrode tab 114 and the second electrode tab 115 to the protection circuit module 130. Connect it. At this time, the first connection lead 140 and the second connection lead 145 is generally formed in an 'L' shape, but the shape is not limited in the present invention.

In addition, after the electrode tabs 114 and 115 and the protection circuit module 130 are electrically connected through the connection leads 140 and 145, as shown in FIG. Fold the second electrode tab 115, the first connection lead 140 and the second connection lead 145 to connect the protective circuit module 130 to the first electrode tab 114 of the pouch sheathing material 120. The second electrode tab 115 is positioned above the withdrawn portion.

2A is a perspective view illustrating a connection lead of a pouch-type lithium secondary battery according to an embodiment of the present invention, and FIG. 2B is a view illustrating a connection lead of a pouch-type lithium secondary battery according to an embodiment of the present invention. It is a section for.

2A and 2B, the connection lead 145 of the pouch-type lithium secondary battery according to the exemplary embodiment of the present invention has a structure integrated with a positive temperature device.

In this case, the connection lead 145 may include an upper conductive layer 145a, a lower conductive layer 145c, and a positive temperature element material layer 145b interposed between the upper conductive layer 145a and the lower conductive layer 145c. It consists of a structure provided. In this case, the upper conductive layer 145a and the lower conductive layer 145c are generally made of nickel (Ni) and equivalents thereof, but the material is not limited thereto.

One of the upper conductive layer 145a and the lower conductive layer 145c, for example, the upper conductive layer 145a may be formed by forming an electrode tab 114 of the pouch-type lithium secondary battery 100 shown in FIG. 1. 115) and one of the protection circuit modules 130, for example, the protection circuit module 130. In this case, the upper conductive layer 145a may be formed of a bonding pad 135 made of a conductive metal such as a nickel (Ni) that is previously attached to the protective circuit module 130 when the protective circuit module 130 is connected to the protective circuit module 130. It is connected via laser welding.

This ensures ease of laser welding through the bonding pads 135, and at the same time, when the bonding pads 135 of the protection circuit module 130 and the connection lead 145 integrated with the positive temperature element are bonded to heat. This is to prevent damage of the positive temperature element material layer 145b.

In addition, the other one of the upper conductive layer 145a and the lower conductive layer 145c, for example, the lower conductive layer 145c may be formed on the electrode tabs of the pouch-type lithium secondary battery 100 shown in FIG. 1. 114, 115 and one of the protection circuit modules 130, for example, a second electrode tab 115 that serves as a negative electrode tab.

At least one of the upper conductive layer 145a and the lower conductive layer 145c, for example, the upper conductive layer 145a electrically connected to the bonding pad 135 of the protective circuit module 130 may have an L shape. However, the shape is not limited in the present invention. In addition, the upper conductive layer 145a and the lower conductive layer 145c may be made of nickel (Ni), a nickel alloy (Ni alloy), and equivalents thereof, but the material is not limited thereto.

The positive temperature element material layer 145b may be formed of a polymer composite, and preferably, carbon is dispersed in styrene butadiene rubber (SBR). In addition, the thickness of the positive temperature element material layer 145b is preferably 0.3 mm or less. This is because when the thickness of the positive temperature element material layer 145b is greater than 0.3 mm, the protective circuit module 130 may have the first electrode tab 114 and the second electrode tab (not shown) of the pouch exterior member 120. When the 115 is positioned above the leaded portion, the protection circuit module 130 is positioned high, and when the pouch-type lithium secondary battery 100 is embedded and combined in a hard case to form a hard pack battery. This is because the pouch-type lithium secondary battery 100 may not be well built and bonded to the hard case.

3A is a perspective view illustrating a connection lead of a pouch-type lithium secondary battery according to another embodiment of the present invention, and FIG. 3B is a cross-sectional view illustrating a connection lead of a pouch-type lithium secondary battery according to another embodiment of the present invention. to be.

3A and 3B, the connection lead 245 of the pouch-type lithium secondary battery according to another embodiment of the present invention is connected to the pouch-type lithium secondary battery illustrated in FIGS. 1A to 1C, 2A and 2B. It is structurally similar to the lead 145. However, only the structure in which the said connection lead 245 consists of the positive temperature element part 245A and the protection circuit module connection part 245B is different.

In more detail, the positive temperature element portion 245A includes a positive temperature element material interposed between an upper conductive layer 245a, a lower conductive layer 245c, and the upper conductive layer 245a and the lower conductive layer 245c. It has a structure having a layer 245b. In addition, the protective circuit module connection part 245B is formed of a predetermined conductive film, and is bonded to any one of the upper conductive film 245a and the lower conductive film 245b, for example, the upper conductive film 245a. It consists of a structure that is electrically connected.

Table 1 below is a chart for explaining the change of the OCV / IR (V / Ω) value of the protection circuit module according to the position of the positive temperature element.

Positive temperature element position Protection circuit module Connection lead OCV / IR (V / Ω) 3.85V / 190mΩ 3.85V / 110 ~ 130Ω

Referring to Table 1, it can be seen that the OCV / IR (V / Ω) value is larger when the positive temperature device is located in the connection leads 140 and 145 than when the positive temperature device is located in the protection circuit module. . That is, it can be seen that the resistance value of the protection circuit module when the positive temperature element is located in the connection lead is small.

Therefore, due to the effect of lowering the self-resistance of the pouch-type lithium secondary battery, the performance of the lithium secondary battery may be improved.

In the pouch-type lithium secondary battery 100 according to the embodiment of the present invention as described above, the connection leads 140, 145, and 245 electrically connecting the electrode assembly 110 and the protection circuit module 130 have positive temperatures. By performing the role of the device, the reaction rate of the positive temperature device is improved compared to the case where the conventional positive temperature device is mounted on the protection circuit module 130. In addition, as the reaction rate of the positive temperature element is improved, the risk of explosion of the pouch-type lithium secondary battery 100 is reduced.

That is, the connection leads 140, 145, and 245 are integrated with the positive temperature element, thereby making it possible to cut off the circuit according to the temperature rise of the pouch-type lithium secondary battery 100 at a faster time. The stability of the pouch type lithium secondary battery 100 is improved. Accordingly, the risk of explosion of the battery pack including the pouch-type lithium secondary battery 100 is reduced.

According to the present invention as described above, the present invention can provide a pouch-type lithium secondary battery with improved stability by the connection lead for electrically connecting the electrode assembly and the protection circuit at the same time as the positive temperature element.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (10)

An electrode assembly having a first electrode plate, a second electrode plate, and a separator interposed between the first electrode plate and the second electrode plate; A pouch case having a space for accommodating the electrode assembly; A protection circuit module for controlling charging and discharging of the electrode assembly, the protective circuit module including a bonding pad at a portion thereof; And a connection lead electrically connected to the bonding pad and the electrode assembly and blocking a circuit when the temperature rises. The method of claim 1, Pouch-type lithium secondary battery, characterized in that the bonding pad is made of nickel. The method of claim 1, And the connection lead comprises an upper conductive film, a lower conductive film, and a positive temperature element material layer interposed between the upper conductive film and the lower conductive film. The method of claim 3, wherein One of the upper conductive film and the lower conductive film is electrically connected to the electrode assembly, The other of the upper conductive layer and the lower conductive layer is a pouch type lithium secondary battery, characterized in that electrically connected to the bonding pad. The method of claim 1, The connection lead A positive temperature element portion having an upper conductive film, a lower conductive film, and a positive temperature element material layer interposed between the upper conductive film and the lower conductive film; A pouch type lithium secondary battery comprising a protective circuit module connection part electrically connected to the bonding pad. The method of claim 5, One of the upper conductive film and the lower conductive film is electrically connected to the protective circuit module connection part. The other of the upper conductive layer and the lower conductive layer is a pouch type lithium secondary battery, characterized in that electrically connected with the electrode assembly. An electrode assembly having a first electrode plate, a second electrode plate, and a separator interposed between the first electrode plate and the second electrode plate; A pouch case having a space for accommodating the electrode assembly; A protection circuit module for controlling charging and discharging of the electrode assembly, the protective circuit module including a bonding pad at a portion thereof; And a connection lead electrically connected to the junction pad and the electrode assembly and integrated with a positive temperature element. The method of claim 7, wherein The connection lead integrated with the positive temperature element is An upper conductive layer electrically connected to the bonding pads; A lower conductive layer electrically connected to the electrode assembly; A pouch type lithium secondary battery comprising a positive temperature element material layer interposed between the upper conductive film and the lower conductive film. The method of claim 7, wherein The connection lead integrated with the positive temperature element is A positive temperature element portion having an upper conductive film, a lower conductive film, and a positive temperature element material layer interposed between the upper conductive film and the lower conductive film; A pouch type lithium secondary battery comprising a protective circuit module connection part electrically connected to the bonding pad. The method of claim 9, One of the upper conductive film and the lower conductive film is electrically connected to the protective circuit module connection part. The other of the upper conductive layer and the lower conductive layer is a pouch type lithium secondary battery, characterized in that electrically connected with the electrode assembly.

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